The study has two major objectives. One is to study the effects of inhaled pollutants on the lung under a variety of circumstances found in industrial and urban environments. The two basic agents are to be sulfur dioxide and a soluble aerosol (NaCl, (NH4)2SO4). The aerosol will have a size-distribution typical of urban aerosols. The second objective is to use mitochondria as sensitive indices of biochemical toxicity in the lung. The mitochondria are to be isolated and assayed for enzymatic composition and function. Cytochemical techniques are to be combined with the assay to permit localization of the mitochondrial changes in situ. Bibliographic references: Watanabe, S. and Frank, R.: Lung volumes, mechanics and single-breath diffusing capacity in anesthetized cats. J. Appl. Physiol. 38(6):1148-1152, 1975. Meyer, P., Behrin, E., Frank, R., Holub, R. and McJilton, C.E.: Biomedical application of shortlived positron emitting isotopes, presented at the Nuclear Cross Section and Technology Meeting, 2-7 March, 1975, Washington, D.C.